Drawing bench



. Feb. 19, 1935.

w. MARTIN DRAWING BENCH Filed March 24, 1927 s Sheets-Sheet 1 vs Q! g zuezz r:

Feb. 19, 1935. w. MARTIN DRAWING BENCH Filed March 24, 1927 3 Sheets-Sheet 2 Feb. 19, 1935. w. MARTIN DRAWING BENCH Filed March 24, 1927 3 Sheets-Sheet 3 Patented Feb. 19, 1935 UNITED STATES PATENT OFFICE 1,992,082 DRAWING BENCH J Application March 2d,

1927!, Serial No. 1755,1211

lln Great Britain February 28, 3192'? d @laims.

This invention relates to animproved drawing bench for closed-end tubes, tubular bodies and the like elongated work-pieces, in which a drawing mandrel is employed, which either separately or together with its shaft must be guided by separate guides.

Hitherto, the mandrel and its shaft were guided by longitudinally movable guide-pieces, which were displaced in any appropriate way in the bench bed during the reciprocation of the mandrel. Said guide-pieces caused frequently various working disturbances and are besides exposed to strong wear while at the same time they result in a wear of the bench bed surfaces serving for guiding the same. Furthermore, by the continuous to and fro movement of the heavy guide-pieces (it being the question of a perpetual alternating acceleration and retardation of reciprocating masses of several hundred kgs. of weight) undue power is consumed.

It has already been proposed to guide the mandrel and its shaft of drawing contrivances serving for similar purposes in an uninterrupted slotted pipe. This proposal has, however, a series of drawbacks: First of all, there exists a sliding friction that requires a great expenditure of power; furthermore, clampings and working disturbances are unavoidable because the guiding means getting easily covered with a foreign material clamps the mandrel and its shaft immovably fast; besides, the mandrel and its shaft are with dificulty accessible and surveyable because they are almost completely enclosed. Finally, the greatest drawback making said kind of guiding practically use less for most of the drawing benches, is that any cooling action is impossible due to the mandrel being enclosed in the guiding bed, this being the principal reason why such proposals were not followed in practice and the known movable single guide-pieces with all their drawbacks above explained were adhered to.

The present invention has for its object to overcomethe drawbacks named, and consists in providing a bench for drawing tubular bodies with a mandrel having a shaft and driven by a machine part, whilst for guiding the mandrel a plurality of guide-pieces are furnished which are non-reciprocating during the guiding operation and are adapted to permit a free passage of said driving machine part through between them.

In this connection, according to the invention constructions are attained, which receive a particular value in such cases where existing drawing benches of any kind are to be changed to embody the improved arrangement.

The accompanying drawings illustrate diagram matically how the invention can be put into practice:

Figures 1 and 2 show side views of the mandrel and its shaft with the guide pieces in two different working positions thereof,

Figures 3 and 4 are end views of the improved arrangement in two difierent constructions thereof,

Figures 5 and 6 are respectively a side view, partly in section, and an end view of a further modification of the rear end of the mandrel shaft with the driving machine part;

Figures 7 and 8 are side views, similar to that shown in Figure 1, of a further modification of the improved arrangement in two difierent positions thereof,

Figure 9 is a vertical cross-sectional view of the form of invention shown in Figure 8,

Figure 10 is a similar view to that illustrated in Figure l, showing a modification thereof.

Figure 11 is a similar view to that illustrated in Figure 1, showing a modification thereof,

Figure 12 is a similar view to that illustrated in Figure 3 showing a modification thereof,

Figure 13 is a similar view to that illustrated in Figure 6, showing a modification thereof,

Figure 14 is a plan view of part of Figure 13, and

Figure 15 is a similar view to that illustrated in Figure 2, showing a modification thereof.

Referring to Figures 1 and 2, the guide pieces for the mandrel and its shaft form oscillatingly suspended bodies a, which by guide rollers 17 partly embrace the mandrel c and its shaft d and which themselves arewell supported in an appropriate way in the bench bed, so that they are also adapted to take-up lateral strains exerted by the mandrel and its shaft.

Instead of the one group of such guide-pieces illustrated, also a plurality of groups in different planes may be arranged.

The operation of the improved drawing bench follows from Fig. 2:-A recess e at the rear end of the shaft allows during the advance of the latter the oscillation of the guide-pieces beyond their mean position, so that they give a free path for the toothed-rack 1. During the return movement of the shaft, the guide-pieces can again turn back to the normal guiding position through the recess e in the rear end of the shaft either by their own weight or by spring action or by permanently acting pullingforces (not illustrated).

Figures 3 and 4 show further constructions, in

which by the particular formation and dimensioning of the cross-section of the toothed rack f, the employment of stationary guide rollers g of primitive kind is possible.

As further shown in Figures 1 and 2 it is also possible and sometimes advantageous to combine the two constructions, viz., oscillatory guide pieces a and shaft guide rollers g.

The improved drawing bench construction has the following technical advantages:

(1) Omission of the heavy movable guide-pieces and of the shocks to which the whole bench is exposed by the same.

(2) Possibility of the employment of rolling friction instead of the hitherto sliding friction.

(3) Saving of power and of the drawing tools.

(4) Increase of the working safety.

(5) More reliable products, because the vibrations of the drawing mandrels and of the whole bench produced by the hitherto used guide-pieces are dispensed with.

(6) Possibility of the employment of higher bench speeds, which results in an essential increase of the capaiity of the drawing bench per unit .of time.

The invention relates also to further constructional forms of the drawing bench just described for tubes, tubular bodies and other elongated work-pieces. Also in these further constructions the guiding of the mandrel and its shaft does no more take place by guide-pieces in any way longitudinally displaceable in the bench bed, but by stationary guide-pieces.

Whereas with the first-mentioned constructions, in which the rear end of the shaft of the drawing mandrel is connected with the drivingtoothed-rack or the like by its being screwed into the latter, the guide-pieces must oscillate for liberating the path for the toothed-rack during the advance of the bench or with stationary guide 'vpieces the driving-toothed-rack must be formed and dimensioned of particular cross-section. The present invention creates also constructional forms, which even with stationary guide-pieces makes a particular construction or formation of the driving-toothed-rack superfluous. This is of particular advantage if existing drawing benches of known kind are to be changed according to the invention.

To this end, the particular construction and formation. of-the toothed-rack with stationaryguide-pieces is' avoided by not inserting or screwing the mandrel shaft, as mentioned, into the face of the toothed-rack but by arranging the shaft and mandrel at such a distance from the machine part driving the same, for instance a toothed-rack, a plunger-rod, endless chain or the like, that said machine part can run or pass along the stationary and fixed mandrel and shaft guides.

rear end of the shaft in clamping jaws arranged on the toothed-rack ends and of which the dimensioning and formation takes place with regard to an unobstructed passage of the drivingtoothed-rack through between the mandrel and shaft guides.

Figures 5 and 6 show this improved construction. The rear end of the shaft is clamped fast between clamping jaws h, the latter being located on the end of the driving toothed-rack and connected therewith by means of bolts effecting at the same time the clamping of the rear end of the shaft. Preferably, the rear end of the shaft and also the clamping jaws receiving the A particularly favourable and simple constructional form is attained'by fastening the same are provided with circumferential notches or grooves 12 for attaining a safe hold of the mandrel therein. Fig. #6 shows clearly how in this construction during the advance of the bench the toothed-rack can unobstructedly slide below the two laterally arranged guide-pieces g and a which are both fixed.

The invention relates further to a series of constructional forms of the improved drawing bench that allow a drawing bench working with an interchange of the drawing mandrels. With this kind of working a large number of drawing mandrels are used and passed through the drawing bench in a continuous circulation. The cooling of the mandrels takes place in this case not in the bench itself but beyond the latter during said circulation. For this purpose, in the circulation of the drawing mandrels, if necessary, a so-called cooling-bed can be inserted, along which roll the mandrels which are exposed to the cooling action of the outer air or of a separate air current.

According to the invention, the drawing bench constructions afore described can be adapted to this special kind of drawing bench working by makingall the guide-pieces for the mandrel and for the shaft respectively, in groups .or separately, displaceable transversely to the longitudinal direction of the drawing bench. Then, a

very easy interchange of the mandrel or of the shaft, or of both of them, is possible by a transverse movement of the same.

The transverse displacement of the trans versely movable guide-pieces can for instance take place separately or in common by means of hydraulically moved members. In this way, for instance, the oscillatingly suspended afore-described guide-pieces a illustrated in Figs. 1, 2, 7, 8, 11 and 15 can be raised and lowered. There are three different possibilities of guiding the mandrel and the mandrel shaft, (1) the guiding may be effected solely by the guide pieces a which move at each operation of the bench in order to make room for the mechanical parts carrying the shaft, for example the rack. (2) The guiding may be effected by fixed bodies 9 as shown for example in Figs. 4, 6, 7 and 11. (3) The guiding may be effected by the oscillatingly mounted parts a and the fixed bodies g as shown for example in Figs. 2 and 9.

In Fig. l guide-pieces l are carried by the plunger-rods of hydraulic cylinders k; Fig. 1 showing the bench at the moment when a fresh drawing mandrel is placed upon the guide-pieces Z in the lowered position of the latter, while Fig. 2 shows the bench with said mandrel put in its working position by lifting the guide-pieces l.

Particularly advantageous constructional forms of the series of construction of the improved drawing bench are obtained by inserting in the members for transversely moving the guidepieces self-locking knee-links 2, such as for instance illustrated in Figs. 11, 13 and 14 in two different constructions thereof. The operation of the knee-links can also be effected hydraulically, and the arrangement can be such that a plurality of guide-pieces can be operated at a time by means of a common hydraulic contrivance x,-Fig. 11.

Figure 10 illustrates how one of the guide pieces g shown in Figure 4 can be operated by means of a hydraulic cylinder k for allowing an easy interchange of the drawing mandrel.

As shown in Figure 12, the guide pieces 9 can be arranged on a turntable flap m that can be -1,99 2,oe2 lifted by hydraulic means and locked in the working position of the guide-pieces by means of \a pawl 0 which, as shown, can be disengaged by the same hydraulic means for lifting said flap.

In all the constructions of the'improved drawing bench, in which the guide-pieces are oscillatingly arranged and. fitted with guide-rollers for the mandrel and its shaft, the guide-pieces can be so-formed and dimensioned that the guide-rollers bear upon the machine part moving the same, for; instance the toothed-rack and roll along the same. Furthermore, in all of said cases, the guide pieces can be fitted with projections n, see Figure 15, forming additional guides for the man- 'drel and its shaft. 3 Instead of by the lower shaft guide rollers l the mandrel and its shaft can simply be guided at the underside with an omission of said rollers, in

the correspondingly grooved bench bed, the latter being then made adjustable in its position of height by means of the contrivance m, z illuschanging the mandrel.

Furthermore, in all ,said cases the guide-pieces can be fitted with lower forked projections forming additional lateral guides for the mandrel and its shaft and, as shown at n in Fig. 9, projecting from above over the upper sides of the mandrel and its shaft, so that the latter are embraced and guarded, against transverse displacements namely, from below by the lower fixed guides g, from both sides by said forked projections 11. and from above by the guide-rollers b of the oscillatingly suspended guide-pieces (1' (shown in section in Fig. 9) whereby a reliable and suflicient guiding of the mandrel and its shaft is attainedand the latter are prevented from bending. In this connection, it must be noted that in the event of disturbancesin the bench working which. might cause a bending of the mandrel and its shaft, there is no slowly increasing pressure of the mandrel and its shaft in upward ,direction against the oscillatingly suspended guide-piecesor their rollers but there areimpulss or shocks only of the mandrel and its shaft against said rollers. Said impulses or shocks, of which the direction passes through the suspension-points of the guide-pieces, are easily met by the latter without the same coming out of their guiding posi-.

tion, their resistance beingquite sufficient to prevent the mandrel and its shaft from bending. -A transverse displacement of the latter in downward and lateral directions is, as already mentioned, prevented by the lower fixed guides y and by the forked projections n of the guide pieces a.

The constructions afore described are by way of example only, other constructions and appropriate combinations thereof being possible within the scope of the present invention.

Preferably, the oscillatory guide-pieces are of light mass, for instance formed as thin-walled hollow bodies of light metal or the like, whereby also a shockproof and noiseless Working of the drawing bench is ensured.

What I claim, is:

l. A bench for hot drawing tubular bodies, comprising in combination a plurality of draw rings for a single blank, a mandrel, a power op- .shifting s'ame'when the tube and mandrel rings, oppositely disposed guides for the mandrel andv shaft, the guides at one side being, arranged ,in two groups, one of said groups bearingon the shaft being fixed against transverse movement wh'le the second group bearing on the mandrelis D tra versely shiftable relative to the longitudinal axis of the mandrel for replacement of the work,

and suitably operated means cooperating withv said 'shiftable group of guides for transversely are withdrawn from the dies. n 2. A bench for hot drawing tubular bodies, comprising in combination a plurality of draw rings for a single blank, a mandrel, a shaft engageable with one end of the mandrel for moving the same through the draw rings, said shaft including a rack drive, sets of guides mounted on both sides of' the mandrel and shaft to brace them against lateral flexure whilst permitting the trated in Figure 11 for the purpose of easily interpassage of the rack drive, one set of guides being arranged in the groups, one group of a length for cooperation vfirst with the' mandrel at the commencement of the drawing stroke and subsequently with the shaft following the mandrel in the course of the drawing stroke, and said last named group being transversely shiftable to permit lateral displacement of the mandrel relative to the shaft and draw rings. v

'3. A bench for hot-drawing tubular bodies, comprising in combination a plurality of draw rings for a single blank, a mandrelfor moving shiftable relative to the longitudinal axis of ,the 40,

mandrel for replacement of the work, and suitably operated meanscooperating with said shiftable group of guides for transversely shifting. same when the tube and mandrel are withdrawn from the dies, said suitably operated means including devices directly engageable with said group of. guides for holding the same inoperative and inoperative positions.

4. A bench for hot drawing tubular comprising in combination a plurality ofdraw rings for a single blank, a mandrel for moving the same through the' draw rings, oppositely dis posed guides for the mandrel and shaft, the guides at one .side being arranged in two groups one of said groupsbearing onthe shaft being fixed against transverse movement while the second group bearing on the mandrel is transversely shiftable relative to the longitudinal axis of the mandrel for replacement of the workand fluid operated means. cooperating with said shiftable group of" guides for transversely shifting same when the tube and mandrel are Withdrawn from the dies, said fluid operated means including debodies,

vices directly engageable with said group of guides for holding the same in operative and inoperative positions; i 

